Bosch SHU66C06UC/14 Needs more diagnostics

DW fills and drains OK but no circulation. Have checked this forum for ideas and have concluded it may be faulty flow switch, pump, or other relays. Have downloaded all diagrams and replacement instructions for this or similar models and have removed right side to view. Unit will go through a cycle according to countdown indicator. Is there a way to diagnose the possibilities w/o tearing into it too much further? I have ohmmeter, tools, and some experience with other appliance repairs. (I successfully replaced the soap dispensor a couple of months ago). Any guidance suggestions gratefully accepted.